Hello, i'd like to know what are th options if you want to develop a game that runs on every mobile device ( ios and android mainly ) except for c#\XNA/Mono. I don't want to use an engine either so i was looking at a cross-platform 2d graphic library.

Just wanted to point out that there is also Cordova from Apache which creates a native stand alone HTML5 / Javascript app that you can very easily port to any platform including iOS, Android, WinPhone, Blackberry and all flavors of PC as well. Might be something to look in to, especially considering it is a mobile game and you are already limited by size and hardware performance issues I would assume that the project itself isn't very complicated. I have ran my own tests on app's (not games) and have found that using Cordova with jQuery you actually get smoother / faster translation animations using Cordova then you do using the native tool kits. With all of that said it's also worth mentioning that the HTML5 canvas element is already using the devices preferred hardware acceleration API (which in these cases in OpenGL).

I'm sure many people will disagree with this approach and of course you should do your research and pick what works best for you. I would just recommend that you at least give my solution a try and see if it's something that can help you. HTML5 games take minutes to setup and get started, within a couple hours you could code up the most complicated part of your game and run it inside an emulator on your PC, if it runs satisfactorily then you can rest assured it will run great on the device. (An android emulator on PC is slower than a first gen android, same with iPhone emulation).

Luckily Windows phone isnt your main target because as an indie developer, you are not eligible for the native SDK and would be pretty much stuck with C#.

Not true of Windows Phone 8, which supports C++ and DirectX. Unfortunately I don't think OpenGL ES is supported, and IIRC DirectX for WinPhone8 is not quite "Big DirectX" but its close enough.

Granted, WinPhone in general is a smallish market, and WinPhone 8 even smaller, but its a nice system, its growing, the app store (from a developers standpoint) is one of the least restrictive and offers a better share of profit, and is less saturated.